I don't really feel like this is particularly telling tbh. £294m net spend for a team largely in the Premier League over the last 10 years seems fine really. Especially considering they don't ever really have players with the resale value that the likes of Real Madrid have to bring down their net spent. They're not really a Brighton who buy smart and recoup a massive profit because they're no longer really in a position to be buying players with an eye on not being relegated. Bournemouth spend relatively average modern day prices but sign several players between the 10-25m range. Their record sale is Nathan Ake at about 40m, and after that it's Danjuma for about 20m.
Comparatively, in the last 10 years Real Madrid have sold Ronaldo for 100m, Di Maria for 65m, Casemiro for 60m, Morata twice for a combined like 85m, Hakimi for 40m, Odegaard for 35m, Reguilon for 30m, Kovacic for 40m.